In heat assisted magnetic recording, information bits are recorded on a data storage medium at elevated temperatures, and the data bit dimension can be determined by the dimensions of the heated area in the storage medium or the dimensions of an area of the storage medium that is subjected to a magnetic field. In one approach, a beam of light is condensed to a small optical spot onto the storage medium to heat a portion of the medium and reduce the magnetic coercivity of the heated portion. Data is then written to the reduced coercivity region.
Current HAMR recording head designs generally have a near field transducer (NFT) that is capable of focusing light to a spot size smaller than the diffraction limit. The NFT is designed to reach local surface-plasmon at a designed light wavelength. At resonance, a high electric field surrounding the NFT appears, due to the collective oscillation of electrons in the metal. A portion of the field will tunnel into the storage medium and get absorbed, raising the temperature of the medium locally for recording.
The NFT's temperature significantly increases at plasmonic resonance. To help dissipate the heat, a heat sink can be added to the NFT that connects to the write pole. This significantly reduces the temperature of NFT. The heat sink may be made of the same plasmonic material as the NFT itself, such as Au, Ag or Cu.